Monsanto Company

Thomas E Waldman

William D McGhee

Dennis Patrick Riley

Michael K Stern

Mark D Paster

A John Solodar

Kenneth W Ruettimann

A process for preparing isocyanates comprising contacting carbon dioxide and a primary amine in the presence of an aprotic organic solvent and a base selected from the group consisting of a phosphazene compound, an organic, nitrogenous base and mixtures thereof, wherein the organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines and mixtures thereof to produce the corresponding ammonium carbamate salt, reacting the ammonium carbamate salt with an anhydride dehydrating agent to produce a product stream comprising the corresponding isocyanate, the aprotic organic solvent and the base salt derived from the anhydride, separating the base salt from the product stream, recovering and recycling the base, and regenerating and recycling the anhydride dehydrating agent.

Process for preparing isocyanates

A process for preparing isocyanates comprising (a) contacting carbon dioxide and a primary amine in the presence of an aprotic organic solvent and a phosphazene compound or a mixture of a phosphazene compound and an organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines, pyridine and mixtures thereof to produce the corresponding ammonium carbamate salt, and (b) reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent to produce the corresponding isocyanate. A second embodiment comprises recovering the ammonium carbamate salt of step (a) prior to reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent in the presence of an aprotic organic solvent and a phosphazene compound or a mixture of a phosphazene compound and an organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines, pyridine and mixtures thereof.

Process for preparing isocyanates using phosphazine catalysts

A process for preparing an isocyanate having at least two --N.dbd.C.dbd.O groups is provided which comprises preparing a substituted aromatic amine having at least two --NH.sub.2 groups, recovering the substituted aromatic amine having at least two --NH.sub.2 groups, and preparing an isocyanate from the substituted aromatic amine having at least two --NH.sub.2 groups by (1) contacting the substituted aromatic amine with CO.sub.2 under conditions sufficient to produce the corresponding ammonium carbamate salt, and reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent under conditions sufficient to produce the corresponding isocyanate, or (2) contacting the substituted aromatic amine with CO.sub.2 under conditions sufficient to produce the corresponding ammonium carbamate salt, reacting the ammonium carbamate salt with a primary or secondary hydrocarbyl halide in a polar aprotic solvent under conditions sufficient to produce the corresponding carbamate ester, and cracking the carbamate ester under conditions sufficient to produce the corresponding isocyanate.

Process for preparing isocyanate and carbamate ester products

A process for preparing isocyanates comprising (a) contacting carbon dioxide and a primary amine in the presence of an aprotic organic solvent and an organic, nitrogenous base to produce the corresponding ammonium carbamate salt, and (b) reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent to produce the corresponding isocyanate. A second embodiment comprises recovering the ammonium carbamate salt of step (a) prior to reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent in the presence of an aprotic organic solvent and an organic, nitrogenous base.

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Chesterfield, MO, United States of America

Thomas E Waldman